JP5458508B2 - Adhesive rubber composition - Google Patents

Description

  The present invention relates to an adhesive rubber composition, and more particularly to an adhesive rubber composition having improved adhesion between rubber and a reinforcing wire cord.

  Adhesion between rubber and wire cord in pneumatic tires is a competitive reaction between the vulcanization reaction of the rubber itself and the adhesion reaction, so a vulcanization accelerator with a slow vulcanization rate is used to make the adhesion advantageous. This is generally done (see Patent Document 1). Conventionally, the vulcanization accelerator DZ (N, N-dicyclohexyl-2-benzothiazolylsulfenamide) is effective for this purpose and is widely used in the rubber industry. However, the vulcanization accelerator DZ has a problem of high cost, and an alternative to an inexpensive vulcanization accelerator has been required to reduce the cost. Therefore, it is conceivable to use a vulcanization accelerator NS (Nt-butyl-2-benzothiazolylsulfenamide), which has a faster vulcanization rate than DZ, as an alternative, but when DZ is simply replaced with NS. There is a problem that adhesiveness deteriorates.

JP 2005-272815 A

  Accordingly, an object of the present invention is to provide an adhesive rubber composition containing a vulcanization accelerator in place of the current vulcanization accelerator DZ by overcoming the problems of the prior art.

According to the present invention, 100 parts by weight of rubber, 0.1 to 0.3 parts by weight of organic acid cobalt salt as a cobalt content, 0.1 to 3 parts by weight of hexamethylenebisthiosulfate disodium salt dihydrate, Sulfur accelerator NS (Nt-butyl-2-benzothiazolylsulfenamide) 0.3 to 0.7 parts by weight, at least one selected from the group consisting of resorcin condensate, modified resorcin condensate and cresol resin There is provided an adhesive rubber composition comprising 0.5 to 5 parts by weight of a seed and 0.5 to 5 parts by weight of a partial condensate of hexamethylol melamine pentamethyl ether and / or a partial condensate of hexamethoxymethylol melamine. The

  According to the present invention, a vulcanization accelerator NS is used in place of the vulcanization accelerator DZ, and further, hexamethylene bisthiosulfate disodium salt dihydrate (HTS) and a specific resin, a curing agent, By blending the organic acid cobalt salt, the adhesiveness between the rubber and the wire cord equal to or higher than that when the vulcanization accelerator DZ is used can be obtained.

As a result of researches to solve the above problems, the present inventors have used a vulcanization accelerator NS, which has a vulcanization speed faster than that of the vulcanization accelerator DZ, as described above. 0.1 to 0.3 parts by weight of cobalt salt as a cobalt content, 0.1 to 3 parts by weight of hexamethylenebisthiosulfate disodium salt dihydrate, and 0.3 to 0.7 of vulcanization accelerator NS 0.5 to 5 parts by weight of at least one selected from the group consisting of parts by weight, a resorcin condensate, a modified resorcin condensate and a cresol resin, and a partial condensate of hexamethylol melamine pentamethyl ether and / or hexamethoxymethylol melamine It has been found that an adhesive rubber composition that achieves the above-described object can be obtained by blending 0.5 to 5 parts by weight of the partial condensate.

  The rubber component used in the adhesive rubber composition of the present invention is not limited to these, but any rubber conventionally used in rubber and wire adhesive rubber compositions such as natural Diene rubbers such as rubber (NR), polyisobutyl rubber (IR), polybutylene rubber (BR), styrene-butadiene copolymer rubber (SBR), etc., alone or as an optional blend, and other diene rubbers The blend rubber etc. which mix | blended this rubber | gum as a small component can be used.

  Examples of the organic acid cobalt salt to be blended in the adhesive rubber composition of the present invention include cobalt naphthenate, cobalt stearate, cobalt tall oil, cobalt rosinate, cobalt neodecanoate, and cobalt neodecanoate. . These organic acid cobalt salts are known compounds and are currently blended in various adhesive compositions and can be easily obtained as commercial products. The compounding amount of the organic acid cobalt salt is 0.1 to 0.3 parts by weight, preferably 0.1 to 0.25 parts by weight as a cobalt content per 100 parts by weight of rubber. If the blending amount is small, the adhesiveness to the wire cord is deteriorated, which is not preferable. On the contrary, if the amount is too large, the breaking property is deteriorated, which is not preferable.

  The hexamethylene bisthiosulfate disodium salt dihydrate blended in the adhesive rubber composition of the present invention is a known compound that has been conventionally used as an anti-reversion agent for the purpose of suppressing deterioration in physical properties during overvulcanization. It can be easily obtained as a commercial product. Hexamethylene bisthiosulfate disodium salt dihydrate is blended in an amount of 0.1 to 3 parts by weight, preferably 0.5 to 2.5 parts by weight, per 100 parts by weight of rubber. If the blending amount is small, the adhesiveness with the wire cord is deteriorated, which is not preferable. On the other hand, if the blending amount is too large, the breaking property is deteriorated and the cost is not preferable.

The vulcanization accelerator NS blended in the adhesive rubber composition of the present invention is a substance conventionally blended in a rubber composition as a vulcanization accelerator. According to the present invention, this vulcanization accelerator NS is added to a rubber. 0.3 to 0.7 parts by weight are blended per 100 parts by weight . If the blending amount is small, the degree of vulcanization is lowered, which is not preferable. Conversely, if the blending amount is too large, the adhesiveness to the wire cord is decreased, which is not preferable.

In the adhesive rubber composition of the present invention, at least one selected from the group consisting of a resorcin condensate, a modified resorcin condensate and a cresol resin is preferably 0.5 to 5 parts by weight, preferably 100 parts by weight of rubber. 1 to 3 parts by weight. If the blending amount is small, the adhesion with the wire cord is deteriorated, which is not preferable. On the other hand, if the blending amount is too large, the breaking property is deteriorated. These compounds are all known compounds and can be easily obtained as commercial products. For example, using Penacolite Resin, B-18-S, B-19-S, B-20-S, B-21-S (Indspec Chemical Corp.), Sumikanol 610 (Sumitomo Chemical), SP7000 (Nippon Shokubai), etc. Can do.

According to the present invention, further, 0.5 to 5 parts by weight, preferably 1 to 4 parts by weight of a partial condensate of hexamethylol melamine pentamethyl ether and / or a partial condensate of hexamethoxymethylol melamine with respect to 100 parts by weight of rubber. Part mix. If the blending amount is small, the adhesion with the wire cord is deteriorated, which is not preferable. On the other hand, if the blending amount is too large, the breaking property is deteriorated. These partial condensates can also be obtained as commercial products. For example, Cyrez964RPC (Cytec Industries Inc), Sumikar 507A (Sumitomo Chemical), etc. can be used.

  In addition to the components described above, the rubber composition according to the present invention includes reinforcing agents (fillers) such as carbon black and silica, vulcanization or crosslinking agents, vulcanization accelerators, various oils, anti-aging agents, plasticizers, and the like. Various additives generally blended for tires and other rubber compositions can be blended, and such additives are kneaded by a general method to form a composition and vulcanized or crosslinked. Can be used for As long as the amount of these additives is not contrary to the object of the present invention, a conventional general amount can be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, it cannot be overemphasized that the scope of the present invention is not limited to these Examples.

Examples 1-4 and Comparative Examples 1-7
Sample preparation In the formulation shown in Table I, the components excluding the vulcanization accelerator and sulfur were kneaded for 5 minutes with a 1.5 liter closed mixer and released when the temperature reached 160 ° C. to obtain a master batch. A vulcanization accelerator and sulfur were kneaded with this master batch with an open roll to obtain a rubber composition. Using this rubber composition, the initial and water-resistant adhesive properties were evaluated by the following test methods. The results are shown in Table I.

  Next, the obtained rubber composition was vulcanized in a 15 × 15 × 0.2 cm mold at 160 ° C. for 20 minutes to prepare a vulcanized rubber sheet. The hardness of the vulcanized rubber was measured by the following test method. It was measured. The results are shown in Table I.

Rubber physical property evaluation test method Hardness: Conforms to JIS K 6253. The larger the value, the more advantageous the tire durability.
Initial adhesiveness: A rubber composition was coated and embedded from both sides of brass plated steel cords (1 × 5 structure) arranged in parallel with each other at an interval of 12.5 mm to obtain a 25 mm wide sheet as a test sample. This test sample was vulcanized at 160 ° C. for 20 minutes, and then the cord was pulled out from the sample in accordance with ASTM D 2229, and evaluated at the time of pulling force (index) and rubber coverage (with rubber)%. Larger numbers are better.
Water-resistant adhesion: The test sample after vulcanization was cut and immersed in warm water at 70 ° C. for 4 weeks, and then evaluated according to ASTM D 2229 in the same manner as described above.

  As is apparent from the results of Table I, a comparison was made with a cobalt salt containing manganobon (C22.5) and HTS compared to Comparative Example 1 (conventional standard example) containing vulcanization accelerator DZ. In Example 2, the water-resistant adhesion is slightly superior, whereas in Example 1 according to the present invention, the water-resistant adhesion is improved as compared to Comparative Example 1, and in Example 2, the resin is changed. In Example 3, both the initial adhesiveness and water-resistant adhesiveness were improved. In Example 3, even when NS was 0.3 phr, the water-resistant adhesiveness was improved. In Example 4, even when the amount of cobalt was increased, both initial adhesiveness and water-resistant adhesiveness were improved. Has been.

  On the other hand, Comparative Example 3 was obtained by changing the vulcanization accelerator of Comparative Example 1 to NS, and the water-resistant adhesiveness deteriorated compared to Comparative Example 1, and Comparative Example 4 was obtained by adding HTS to Comparative Example 3. Compared with Comparative Example 4, the water-resistant adhesiveness deteriorated with respect to 1, and HTS was removed and PMMM and a modified resorcin resin were added. There is no improvement. Further, Comparative Example 6 shows that even if a resin is added, if the amount of NS is small, initial adhesiveness and water-resistant adhesiveness are deteriorated. It shows that

  As described above, according to the present invention, the vulcanization accelerator NS is used in place of the vulcanization accelerator DZ, and further, hexamethylene bisthiosulfate disodium salt dihydrate (HTS) and a specific resin are used. Adhesive composition for tire cords, etc., by adding a curing agent and an organic acid cobalt salt to obtain a rubber and wire cord adhesive equivalent to or better than when vulcanization accelerator DZ is used Useful as.

Claims (1)

100 parts by weight of rubber, 0.1 to 0.3 parts by weight of organic acid cobalt salt as cobalt content, 0.1 to 3 parts by weight of hexamethylenebisthiosulfate disodium salt dihydrate, vulcanization accelerator NS (N -t- butyl-2-benzothiazolyl sulfenamide) 0.3 to 0.7 parts by weight, 0.5 to at least one selected from the group consisting of resorcinol condensate, modified resorcinol condensate and cresol resins An adhesive rubber composition comprising 5 parts by weight and 0.5 to 5 parts by weight of a partial condensate of hexamethylol melamine pentamethyl ether and / or a partial condensate of hexamethoxymethylol melamine.